mksnap_ffs.c revision 138559 
1/*
2 * Copyright (c) 2003 Networks Associates Technology, Inc.
3 * All rights reserved.
4 *
5 * This software was developed for the FreeBSD Project by Marshall
6 * Kirk McKusick and Network Associates Laboratories, the Security
7 * Research Division of Network Associates, Inc. under DARPA/SPAWAR
8 * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
9 * research program.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. The names of the authors may not be used to endorse or promote
20 *    products derived from this software without specific prior written
21 *    permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * $FreeBSD: head/sbin/mksnap_ffs/mksnap_ffs.c 138559 2004-12-08 11:54:50Z phk $
36 */
37
38#include <sys/param.h>
39#include <sys/mount.h>
40#include <sys/stat.h>
41#include <ufs/ufs/ufsmount.h>
42#include <err.h>
43#include <errno.h>
44#include <fcntl.h>
45#include <grp.h>
46#include <limits.h>
47#include <stdio.h>
48#include <stdlib.h>
49#include <string.h>
50#include <sysexits.h>
51#include <unistd.h>
52
53void usage(void);
54
55int
56main(int argc, char **argv)
57{
58	char *dir, *cp, path[PATH_MAX];
59	struct statfs stfsbuf;
60	struct ufs_args args;
61	struct group *grp;
62	struct stat stbuf;
63	int fd;
64
65	if (argc != 3)
66		usage();
67
68	dir = argv[1];
69	memset(&args, 0, sizeof args);
70	args.fspec = argv[2];
71
72	/*
73	 * Check that the user running this program has permission
74	 * to create and remove a snapshot file from the directory
75	 * in which they have requested to have it made. If the
76	 * directory is sticky and not owned by the user, then they
77	 * will not be able to remove the snapshot when they are
78	 * done with it.
79	 */
80	if (strlen(args.fspec) >= PATH_MAX)
81		errx(1, "pathname too long %s", args.fspec);
82	cp = strrchr(args.fspec, '/');
83	if (cp == NULL) {
84		strlcpy(path, ".", PATH_MAX);
85	} else if (cp == args.fspec) {
86		strlcpy(path, "/", PATH_MAX);
87	} else {
88		strlcpy(path, args.fspec, cp - args.fspec + 1);
89	}
90	if (statfs(path, &stfsbuf) < 0)
91		err(1, "%s", path);
92	if (stat(path, &stbuf) < 0)
93		err(1, "%s", path);
94	if (!S_ISDIR(stbuf.st_mode))
95		errx(1, "%s: Not a directory", path);
96	if (access(path, W_OK) < 0)
97		err(1, "Lack write permission in %s", path);
98	if ((stbuf.st_mode & S_ISTXT) && stbuf.st_uid != getuid())
99		errx(1, "Lack write permission in %s: Sticky bit set", path);
100
101	/*
102	 * Having verified access to the directory in which the
103	 * snapshot is to be built, proceed with creating it.
104	 */
105	if ((grp = getgrnam("operator")) == NULL)
106		errx(1, "Cannot retrieve operator gid");
107	if (mount("ufs", dir, MNT_UPDATE | MNT_SNAPSHOT | stfsbuf.f_flags,
108	    &args) < 0)
109		err(1, "Cannot create %s", args.fspec);
110	if ((fd = open(args.fspec, O_RDONLY)) < 0)
111		err(1, "Cannot open %s", args.fspec);
112	if (fstat(fd, &stbuf) != 0)
113		err(1, "Cannot stat %s", args.fspec);
114	if ((stbuf.st_flags & SF_SNAPSHOT) == 0)
115		errx(1, "File %s is not a snapshot", args.fspec);
116	if (fchown(fd, -1, grp->gr_gid) != 0)
117		err(1, "Cannot chown %s", args.fspec);
118	if (fchmod(fd, S_IRUSR | S_IRGRP) != 0)
119		err(1, "Cannot chmod %s", args.fspec);
120
121	exit(EXIT_SUCCESS);
122}
123
124void
125usage()
126{
127
128	fprintf(stderr, "usage: mksnap_ffs mountpoint snapshot_name\n");
129	exit(EX_USAGE);
130}
131